Calcium
Compact bone.
Calcium.
Calcium makes them hard.
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Cortical bone tissue makes up the dense hard outer layer of bone. It is also known as compact bone and provides structure and protection to the inner spongy bone tissue.
By definition all bone is hard. Before bone is fully formed it is made of cartilage and so is softer but it is not called bone at that time in development. Bone is made of hydroxyapetite mainly a calcium and phosphate salt. This makes it hard.
Calcified bones are hard but not really solid. Spongy bone is hard with tiny holes in it. Periosteum is thin but very strong. The other name for it is outer membrane, it helps to rebuild bone cells. The last is cartilage. It is strong material that holds two bones together and allows them to glide over one another. Skull iz also a very strong bone.
The strength and rigidity of the bone is a result of the inorganic salts deposited in the matrix. Matrix is basically just large amount of non-cellular materials, which is what your bones are made of.
it makes thing hard to do
Your broken bone
Osteonic canals contain blood vessels that connect to the long axis of the bone. The blood vessels that are connected perforate the canals of the bone and provide vessels to the surface of the bone which makes the bone hard.
its a wierd thing and the brain is full of blood so makes the nerves become hard because dried up blood makes nerves and when something touches the nerves the dried blood scraped against a bone or another organ which makes it hurt !!